In general, a transmitting stage or a receiving stage of a semiconductor integrated circuit is coupled to a termination resistor having the same resistance as an impedance of a transmission channel. The termination resistor may match the impedance of the transmission channel with an impedance of the transmitting or receiving stage to suppress reflection of signals (including data) transmitted through the transmission channel.
In integrated circuits such as central processing units (CPUs) or graphic memory devices, which have relatively low restrictions in terms of power consumption, a termination resistor electrically coupled to a receiving stage has been widely employed to effectively suppress the signal reflection. However, in the event that the termination resistor is electrically coupled to the receiving stage, a direct current (DC) always flows through the termination resistor to cause high power consumption. Thus, it may be difficult to use a design scheme employing the termination resistor coupled to the receiving stage in some integrated circuits such as mobile devices or systems having a relatively high restriction in terms of power consumption. Accordingly, mobile devices or systems having relatively high restrictions in power consumption employ a design scheme in which the termination resistor is coupled to a transmitting stage.
The design scheme having the termination resistor coupled to the transmitting stage may be implemented using a signal transmission circuit. More specifically, integrated circuits may include a transmission circuit that is coupled to the transmitting stage to transmit signals through a transmission channel, and an impedance of the transmission channel may be matched with an impedance of the transmission stage by controlling electrical resistance of the transmission circuit. The transmission circuit may include a plurality of drivers for driving the signals transmitted through the transmission channel. The electrical resistance of the transmission circuit may be controlled by selectively turning on at least one of the plurality of drivers.